INTERACTIONS BETWEEN TARANTULAS (APHONOPELMA HENTZI) AND NARROW-MOUTHED TOADS (GASTROPHYRNE OLIVACEA): SUPPORT FOR A SYMBIOTIC RELATIONSHIP

Abstract

The Great Plains narrow-mouthed toad, Gastrophryne olivacea often shares burrows with other vertebrates (lizards) and invertebrates (spiders and insects). The association with large tarantulas (Aphonopelma hentzi) is particularly interesting because these spiders are opportunistic feeders that readily attack and consume vertebrate prey including anurans. We show that A. hentzi will attack and consume the cricket frog (Acris crepitans) which is similar in size to G. olivacea. In trials where G. olivacea
and more palatable A. crepitans and invertebrates were presented simultaneously to tarantulas, the presence of G. olivacea did not appear to affect the predatory response of the tarantulas. However, when placed in a confined space with G. olivacea or G. carolinensis, the tarantulas never initiated a predatory response. Because we were using wild caught, adult tarantulas, this may be a learned response towards G. olivacea. We have no field records that tarantulas share burrows with G. carolinensis. The  laboratory experiments suggest that tarantulas are sensitized to Gastrophryne spp. and may be able to detect chemicals secreted by the toads.